Developing a novel functional disc emulator to investigate the nucleus pulposus replacement

Area of Science:

• Biomechanical Engineering
• Spinal Mechanics
• Biomaterials Science

Background:

• Spinal motion segments are complex skeletal systems.
• Understanding the mechanical behavior of lumbar intervertebral discs is crucial for developing effective treatments.
• Current methods for evaluating disc mechanics often involve complex and variable cadaveric studies.

Purpose of the Study:

• To develop a simple, inexpensive, and innovative device to reproduce the mechanical behavior of spinal motion segments.
• To create an accurate local mechanical environment for lumbar intervertebral discs.
• To facilitate the exploration of spinal mechanics, tissue characteristics, and evaluation of repair/replacement strategies.

Main Methods:

• Development of a
• disc emulator
• device with adjustable components.
• The emulator includes an artificial annulus fibrosus (AAF) made of silicone and a hydrogel nucleus pulposus (NP), both with lumbar disc geometry.
• Simulated vertebral bodies were 3D printed using ABS and TPU polymers.
• Mechanical compression experiments were performed, and artificial annulus fibrosus bulging was analyzed using digital image correlation (DIC).

Main Results:

• The disc emulator successfully reproduced the global mechanical behavior of spinal motion segments.
• DIC analysis showed close agreement between the emulator's artificial annulus fibrosus bulging and published data from human cadaver samples.
• The device provides an accurate local stress/strain environment for material evaluation.

Conclusions:

• The developed disc emulator is a valuable tool for studying spinal mechanics.
• This innovative device offers a reproducible and accurate method for preliminary material evaluation in spinal research.
• It overcomes the variability and difficulties associated with direct testing of cadaveric materials.